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.TH T_OPEN 3NSL "Feb 17, 2023"
.SH NAME
t_open \- establish a transport endpoint
.SH SYNOPSIS
.nf
#include <xti.h>
#include <fcntl.h>




\fBint\fR \fBt_open\fR(\fBconst char *\fR\fIname\fR, \fBint\fR \fIoflag\fR, \fBstruct t_info *\fR\fIinfo\fR);
.fi

.SH DESCRIPTION
This routine is part of the \fBXTI\fR interfaces which evolved from the
\fBTLI\fR interfaces. \fBXTI\fR represents the future evolution of these
interfaces. However, \fBTLI\fR interfaces are supported for compatibility. When
using a \fBTLI\fR routine that has the same name as an \fBXTI\fR routine, the
\fBtiuser.h\fR header file must be used.  Refer to the  \fBTLI\fR
\fBCOMPATIBILITY\fR section for a description of differences between the two
interfaces.
.sp
.LP
The \fBt_open()\fR function must be called as the first step in the
initialization of a transport endpoint. This function establishes a transport
endpoint by supplying a transport provider identifier that indicates a
particular transport provider, that is, transport protocol, and returning a
file descriptor that identifies that endpoint.
.sp
.LP
The argument \fIname\fR points to a transport provider identifier and
\fIoflag\fR identifies any open flags, as in \fBopen\fR(2). The argument
\fIoflag\fR is constructed from  \fBO_RDWR\fR optionally bitwise
inclusive-OR'ed with  \fBO_NONBLOCK.\fR These flags are defined by the header
\fB<fcntl.h>\fR\&. The file descriptor returned by \fBt_open()\fR will be used
by all subsequent functions to identify the particular local transport
endpoint.
.sp
.LP
This function also returns various default characteristics of the underlying
transport protocol by setting fields in the \fBt_info\fR structure. This
argument points to a \fBt_info\fR which contains the following members:
.sp
.in +2
.nf
t_scalar_t addr;        /* max size of the transport protocol address */
t_scalar_t options;     /* max number of bytes of  */
	                        /* protocol-specific options  */
t_scalar_t tsdu;        /* max size of a transport service data  */
	                        /* unit (TSDU)  */
t_scalar_t etsdu;       /* max size of an expedited transport  */
	                        /* service data unit (ETSDU)  */
t_scalar_t connect;     /* max amount of data allowed on  */
                        /* connection establishment functions  */
t_scalar_t discon;      /* max amount of data allowed on  */
                        /* t_snddis() and t_rcvdis() functions  */
t_scalar_t servtype;    /* service type supported by the  */
	                        /* transport provider  */
t_scalar_t flags;       /* other info about the transport provider  */
.fi
.in -2

.sp
.LP
The values of the fields have the following meanings:
.sp
.ne 2
.na
\fB\fIaddr\fR\fR
.ad
.RS 12n
A value greater than zero (\fBT_NULL\fR) indicates the maximum size of a
transport protocol address and a value of -2 (\fBT_INVALID\fR) specifies that
the transport provider does not provide user access to transport protocol
addresses.
.RE

.sp
.ne 2
.na
\fB\fIoptions\fR\fR
.ad
.RS 12n
A value greater than zero (\fBT_NULL\fR) indicates the maximum number of bytes
of protocol-specific options supported by the provider, and a value of -2
(\fBT_INVALID\fR) specifies that the transport provider does not support
user-settable options.
.RE

.sp
.ne 2
.na
\fB\fItsdu\fR\fR
.ad
.RS 12n
A value greater than zero (\fBT_NULL\fR specifies the maximum size of a
transport service data unit (TSDU); a value of zero (\fBT_NULL\fR) specifies
that the transport provider does not support the concept of TSDU, although it
does support the sending of a data stream with no logical boundaries preserved
across a connection; a value of -1 (\fBT_INFINITE\fR) specifies that there is
no limit to the size of a TSDU; and a value of -2 (\fBT_INVALID\fR) specifies
that the transfer of normal data is not supported by the transport provider.
.RE

.sp
.ne 2
.na
\fB\fIetsdu\fR\fR
.ad
.RS 12n
A value greater than zero (\fBT_NULL\fR) specifies the maximum size of an
expedited transport service data unit (ETSDU); a value of zero (\fBT_NULL\fR)
specifies that the transport provider does not support the concept of ETSDU,
although it does support the sending of an expedited data stream with no
logical boundaries preserved across a connection; a value of -1
(\fBT_INFINITE\fR)  specifies that there is no limit on the size of an ETSDU;
and a value of -2 (\fBT_INVALID\fR) specifies that the transfer of expedited
data is not supported by the transport provider. Note that the semantics of
expedited data may be quite different for different transport providers.
.RE

.sp
.ne 2
.na
\fB\fIconnect\fR\fR
.ad
.RS 12n
A value greater than zero (\fBT_NULL\fR) specifies the maximum amount of data
that may be associated with connection establishment functions, and a value of
-2 (\fBT_INVALID\fR) specifies that the transport provider does not allow data
to be sent with connection establishment functions.
.RE

.sp
.ne 2
.na
\fB\fIdiscon\fR\fR
.ad
.RS 12n
If the  \fBT_ORDRELDATA\fR bit in flags is clear, a value greater than zero
(\fBT_NULL\fR) specifies the maximum amount of data that may be associated with
the \fBt_snddis\fR(3NSL) and \fBt_rcvdis\fR(3NSL) functions, and a value of -2
(\fBT_INVALID\fR) specifies that the transport provider does not allow data to
be sent with the abortive release functions. If the  \fBT_ORDRELDATA\fR bit is
set in flags, a value greater than zero (\fBT_NULL\fR) specifies the maximum
number of octets that may be associated with the \fBt_sndreldata()\fR,
\fBt_rcvreldata()\fR, \fBt_snddis\fR(3NSL) and  \fBt_rcvdis\fR(3NSL) functions.
.RE

.sp
.ne 2
.na
\fB\fIservtype\fR\fR
.ad
.RS 12n
This field specifies the service type supported by the transport provider, as
described below.
.RE

.sp
.ne 2
.na
\fB\fIflags\fR\fR
.ad
.RS 12n
This is a bit field used to specify other information about the  communications
provider.  If the  \fBT_ORDRELDATA\fR bit is set, the communications provider
supports user data to be sent with an orderly release. If the  \fBT_SENDZERO\fR
bit is set in flags, this indicates the underlying transport provider supports
the sending of zero-length TSDUs.
.RE

.sp
.LP
If a transport user is concerned with protocol independence, the above sizes
may be accessed to determine how large the buffers must be to hold each piece
of information. Alternatively, the \fBt_alloc\fR(3NSL) function may be used to
allocate these buffers. An error will result if a transport user exceeds the
allowed data size on any function.
.sp
.LP
The \fIservtype\fR field of \fIinfo\fR specifies one of the following values on
return:
.sp
.ne 2
.na
\fB\fBT_COTS\fR \fR
.ad
.RS 15n
The transport provider supports a connection-mode service but does not support
the optional orderly release facility.
.RE

.sp
.ne 2
.na
\fB\fBT_COTS_ORD\fR \fR
.ad
.RS 15n
The transport provider supports a connection-mode service with the optional
orderly release facility.
.RE

.sp
.ne 2
.na
\fB\fBT_CLTS\fR \fR
.ad
.RS 15n
The transport provider supports a connectionless-mode service. For this service
type, \fBt_open()\fR will return -2 (\fBT_INVALID\fR) for \fIetsdu\fR,
\fIconnect\fR and \fIdiscon\fR.
.RE

.sp
.LP
A single transport endpoint may support only one of the above services at one
time.
.sp
.LP
If \fIinfo\fR is set to a null pointer by the transport user, no protocol
information is returned by \fBt_open()\fR.
.SH RETURN VALUES
A valid file descriptor is returned upon successful completion.  Otherwise, a
value of -1 is returned and \fBt_errno\fR is set to indicate an error.
.SH VALID STATES
\fBT_UNINIT\fR.
.SH ERRORS
On failure, \fBt_errno\fR is set to the following:
.sp
.ne 2
.na
\fB\fBTBADFLAG\fR\fR
.ad
.RS 12n
An invalid flag is specified.
.RE

.sp
.ne 2
.na
\fB\fBTBADNAME\fR\fR
.ad
.RS 12n
Invalid transport provider name.
.RE

.sp
.ne 2
.na
\fB\fBTPROTO\fR\fR
.ad
.RS 12n
This error indicates that a communication problem has been detected between XTI
and the transport provider for which there is no other suitable XTI error
\fB(t_errno)\fR.
.RE

.sp
.ne 2
.na
\fB\fBTSYSERR\fR\fR
.ad
.RS 12n
A system error has occurred during execution of this function.
.RE

.SH TLI COMPATIBILITY
The \fBXTI\fR and \fBTLI\fR interface definitions have common names but use
different header files. This and other semantic differences between the two
interfaces are described in the subsections below.
.SS "Interface Header"
The \fBXTI\fR interfaces use the \fBxti.h\fR. \fBTLI\fR interfaces should
\fInot\fR use this header.  They should use the header:
.br
.in +2
#include <tiuser.h>
.in -2
.SS "Error Description Values"
The \fBt_errno\fR values \fBTPROTO\fR and \fBTBADNAME\fR can be set by the
\fBXTI\fR interface but cannot be set by the \fBTLI\fR interface.
.SS "Notes"
For \fBTLI\fR, the \fBt_info\fR structure referenced by \fIinfo\fR lacks the
following structure member:
.sp
.in +2
.nf
t_scalar_t flags;    /* other info about the transport provider */
.fi
.in -2

.sp
.LP
This member was added to \fBstruct\fR \fBt_info\fR in the \fBXTI\fR interfaces.
.sp
.LP
When a value of -1 is observed as the return value in various \fBt_info\fR
structure members, it signifies that the transport provider can handle an
infinite length buffer for a corresponding attribute, such as address data,
option data, \fBTSDU\fR (octet size), \fBETSDU\fR (octet size), connection
data, and disconnection data. The corresponding structure members are
\fBaddr\fR, \fBoptions\fR, \fBtsdu\fR, \fBestdu\fR, \fBconnect\fR, and
\fBdiscon\fR, respectively.
.SH ATTRIBUTES
See \fBattributes\fR(7)  for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT Level	Safe
.TE

.SH SEE ALSO
.BR open (2),
.BR attributes (7)
